Wireless power transmission device and wireless power transmission system

1. A wireless power transmission system comprising: a wireless power transmission device for wirelessly transmitting power to a wireless power receiving device; and the wireless power receiving device, wherein the wireless power transmission device comprises: a power transmission coil; a power transmission circuit configured to supply alternating current (AC) power to the power transmission coil; and a power transmission side communication circuit configured to communicate with the wireless power receiving device, wherein the power transmission circuit is configured to supply a first AC power to the power transmission coil, wherein the first AC power is an AC power having an intermittent supply period in an intermittent pattern representing identification information of the power transmission side communication circuit, and wherein the power transmission coil is configured to receive the first AC power and generate a first AC magnetic field corresponding to the intermittent pattern, wherein the wireless power receiving device includes: a power receiving coil; a power receiving circuit configured to convert an AC power received by the power receiving coil and supply the converted AC power to a load; and a power receiving side communication circuit configured to communicate with the power transmission side communication circuit, and wherein the power receiving side communication circuit starts an authentication process with the power transmission side communication circuit based on the identification information detected from the first AC power received by the power receiving coil via the first AC magnetic field, wherein the wireless power transmission system further comprises: an output detection circuit configured to detect an output from the power receiving circuit; and an identification information detection circuit configured to detect the identification information from the first AC power received by the power receiving coil when the output detected by the output detection circuit exceeds a first threshold value, wherein the first threshold value is the output detected by the output detection circuit with the first AC power received by the power receiving coil when a relative position between the power transmission coil and the power receiving coil is in a predetermined arrangement.

2. The wireless power transmission system according to claim 1 , wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to detection of approach of the wireless power receiving device to the wireless power transmission device.

3. The wireless power transmission system according to claim 2 , wherein the wireless power transmission device further comprises a proximity sensor configured to detect the approach of the wireless power receiving device to the wireless power transmission device, wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to the detection of the approach of the wireless power receiving device to the wireless power transmission device by the proximity sensor.

4. The wireless power transmission system according to claim 2 , wherein the wireless power transmission device further comprise a position information acquisition unit configured to acquire position information of a moving object on which the wireless power receiving device is mounted, wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to the detection of the approach of the wireless power receiving device to the wireless power transmission device based on the position information.

5. The wireless power transmission system according to claim 1 , wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to activation of the wireless power transmission device.

6. The wireless power transmission system according to claim 1 , wherein the power transmission circuit intermittently supplies the first AC power, and an intermittent cycle in which the power transmission circuit intermittently supplies the first AC power is longer than a cycle of the intermittent pattern.

7. The wireless power transmission system according to claim 1 , further comprising a current detection circuit configured to detect a current of AC power supplied from the power transmission circuit to the power transmission coil, wherein the power transmission circuit is configured to supply a second AC power greater than the first AC power to the power transmission coil in response to completion of the authentication process of the power transmission side communication circuit, and the power transmission circuit is configured to stop the supply of the second AC power to the power transmission coil when the current of the second AC power detected by the current detection circuit exceeds a second threshold value and resumes the supply of the second AC power to the power transmission coil after an elapse of a predetermined time period.

8. The wireless power transmission system according to claim 7 , wherein the power transmission circuit is configured not to resume the supply of the second AC power to the power transmission coil when the number of operations of stopping the supply of the second AC power to the power transmission coil exceeds a predetermined number of times.

9. The wireless power transmission system according to claim 7 , further comprising a load voltage detection circuit configured to detect a voltage of the load, wherein the power transmission circuit configured to: stop the supply of the second AC power and resume the supply of the first AC power when the voltage detected by the load voltage detection circuit exceeds a third threshold value; and resume the supply of the second AC power after resuming the supply of the first AC power when the voltage detected by the load voltage detection circuit is less than a fourth threshold value, which is less than the third threshold value, and the power receiving side communication circuit has completed the authentication process with the power transmission side communication circuit based on the identification information detected from the first AC power.

10. A wireless power transmission system comprising: a wireless power transmission device for wirelessly transmitting power to a wireless power receiving device; and the wireless power receiving device, wherein the wireless power transmission device comprises: a power transmission coil; a power transmission circuit configured to supply alternating current (AC) power to the power transmission coil; and a power transmission side communication circuit configured to communicate with the wireless power receiving device, wherein the power transmission circuit is configured to supply a first AC power to the power transmission coil, wherein the first AC power is an AC power having an intermittent supply period in an intermittent pattern representing identification information of the power transmission side communication circuit, and wherein the power transmission coil is configured to receive the first AC power and generate a first AC magnetic field corresponding to the intermittent pattern, wherein the wireless power receiving device includes: a power receiving coil; a power receiving circuit configured to convert an AC power received by the power receiving coil and supply the converted AC power to a load; and a power receiving side communication circuit configured to communicate with the power transmission side communication circuit, and wherein the power receiving side communication circuit starts an authentication process with the power transmission side communication circuit based on the identification information detected from the first AC power received by the power receiving coil via the first AC magnetic field, wherein the wireless power transmission system further comprises a load voltage detection circuit configured to detect a voltage of the load, wherein the power transmission circuit configured to: supply a second AC power, which is greater than the first AC power, to the power transmission coil in response to completion of the authentication process of the power transmission side communication circuit; stop the supply of the second AC power and resume the supply of the first AC power when the voltage detected by the load voltage detection circuit exceeds a third threshold value; and resume the supply of the second AC power after resuming the supply of the first AC power when the voltage detected by the load voltage detection circuit is less than a fourth threshold value, which is less than the third threshold value, and the power receiving side communication circuit has completed the authentication process with the power transmission side communication circuit based on the identification information detected from the first AC power.

11. The wireless power transmission system according to claim 10 , wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to detection of approach of the wireless power receiving device to the wireless power transmission device.

12. The wireless power transmission system according to claim 11 , wherein the wireless power transmission device further comprises a proximity sensor configured to detect the approach of the wireless power receiving device to the wireless power transmission device, wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to the detection of the approach of the wireless power receiving device to the wireless power transmission device by the proximity sensor.

13. The wireless power transmission system according to claim 11 , wherein the wireless power transmission device further comprise a position information acquisition unit configured to acquire position information of a moving object on which the wireless power receiving device is mounted, wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to the detection of the approach of the wireless power receiving device to the wireless power transmission device based on the position information.

14. The wireless power transmission system according to claim 10 , wherein the power transmission circuit is configured to supply the first AC power to the power transmission coil in response to activation of the wireless power transmission device.

15. The wireless power transmission system according to claim 10 , wherein the power transmission circuit intermittently supplies the first AC power, and an intermittent cycle in which the power transmission circuit intermittently supplies the first AC power is longer than a cycle of the intermittent pattern.